FA-72774 / Check-digit algorithms / Member archive

LEI check digits lose the leading zero · case 04

Check values below 10 produce a 19-character LEI.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Generate ISO 17442 LEI check digits (ISO 7064 MOD 97-10): the 18-character alphanumeric prefix is upper-cased (other input returns None), "00" is appended, letters become 10..35, and the check is 98 - (number mod 97) written as exactly two digits. Return the 20-character LEI.

Why this case matters

Regulatory reporting tools assign and verify legal entity identifiers.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression ["64WI551TBNLAZEBU15"]	`"64WI551TBNLAZEBU152"`	`"64WI551TBNLAZEBU1502"`	Failed

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